sus·tain 
(sə-stān)
(sə-stān)tr.v. sus·tained, sus·tain·ing, sus·tains
1.
a. To keep in existence; maintain, continue, or prolong: sustain an effort.
b. To keep up (a joke or assumed role, for example) competently.
2.
a. To supply with necessities or nourishment; provide for: the income needed to sustain a family.
b. To support the spirits, vitality, or resolution of; encourage: We were sustained by her unflagging optimism.
3. To support from below; keep from falling or sinking; prop: The beams sustain the weight of the roof.
4.
a. To bear up under; withstand: can't sustain the blistering heat.
b. To experience or suffer: sustained minor injuries.
5. To affirm the validity of: The judge has sustained the prosecutor's objection.
n.
A capacity of a musical instrument to continue the resounding of a note or tone.
[Middle English sustenen, from Old French sustenir, from Latin sustinēre : sub-, from below; see SUB- + tenēre, to hold; see ten- in the Appendix of Indo-European roots.]
sus·tainer n.
sus·tainment n.